Method for combining proton beam irradiation and magnetic resonance imaging

ABSTRACT

A method which coordinates proton beam irradiation with an open magnetic resonance imaging (MRI) unit to achieve near-simultaneous, noninvasive localization and radiotherapy of various cell lines in various anatomic locations. A reference image of the target aids in determining a treatment plan and repositioning the patient within the MRI unit for later treatments. The patient is located within the MRI unit so that the target and the proton beam are coincident. MRI monitors the location of the target. Target irradiation occurs when the target and the proton beam are coincident as indicated by the MRI monitoring. The patient rotates relative to the radiation source. The target again undergoes monitoring and selective irradiation. The rotation and selective irradiation during MRI monitoring repeats according to the treatment plan.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.09/754,852, filed Jan. 4, 2001, now U.S. Pat. No. 6,725,078 which claimsbenefit of U.S. application Ser. No. 60/179,271, filed Jan. 31, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to systems for localization andradiotherapy of various cell lines in various anatomic locations. Inparticular, this invention relates to a system which coordinates protonbeam irradiation with an open magnetic resonance imaging (MRI) unit toachieve near-simultaneous, noninvasive localization and radiotherapy ofvarious cell lines in various anatomic locations by maintainingcoincidence between the target and the proton beam.

2. Description of the Prior Art

Proton beam irradiation therapy treats tumors found in selectedlocations that are not subject to significant physiologic motion.Examples of such tumors include prostatic cancer, spinal chordomas, andcertain retinal or orbital tumors. The proton beam generated by amedical cyclotron has similar biological activity for the destruction oftumors as standard radiation therapy techniques to target a fixed tumorsite with minimal radiotoxicity to the surrounding normal tissues.Because protons of a specific energy have a specific penetration depth,adjusting the specific energy of the protons manipulates the distancethe proton beam travels into the patient. Because protons deposit mostof their energy at the end of the penetration depth, the highestconcentration of radiation occurs in the area around the penetrationdepth. This area is known as the Bragg peak of the proton beam.

The focused delivery of protons to a fixed site permits the radiotherapyof tumors or the destruction of tissue causing functional problems.However, tumors and tissue located in organs subject to significantphysiologic motion cannot be treated without significant collateralradiotoxicity. There is a need for a system which allows proton beamdelivery to a target subject to significant physiologic motion thatminimizes the collateral damage to the surrounding normal tissues.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a system which treats atarget within a body of a patient by proton beam therapy by using ascanner to locate the target.

It is another object of this invention to provide a system whichcoordinates a treatment volume such as a Bragg peak of a proton beamwith a target detected noninvasively such as a tumor or dysfunctionaltissue to be destroyed as detected by MRI.

It is another object of this invention to provide such a system whichincludes a patient support device to position the patient so that thetarget is located within the treatment volume.

It is another object of this invention to provide such a system whichincludes a patient support device that allows irradiation of the targetat multiple angles while maintaining coincidence between the target andthe treatment volume.

It is another object of this invention to provide a system which treatsa target within a body of a patient by proton beam therapy by allowingirradiation of the target at multiple angles according to a treatmentplan while minimizing radiation of surrounding tissues during thephysiologic motion of the target.

It is another object of this invention to provide a method forirradiating at multiple angles a target subject to significantphysiologic motion within a body of patient.

In one form, the invention comprises a system for treating a targetwithin a body of a patient comprising a radiating apparatus, a patientsupport, a scanner, and a controller. The radiating apparatus irradiatesa treatment volume having a known position. The patient support supportsthe patient such that the target to be treated is located coincidentwith or adjacent to the treatment volume. The scanner scans the body andcreates body images. The controller selectively activates the radiatingapparatus to irradiate the target when the target is at least partiallycoincident with the treatment volume.

In another form, the invention includes a method for treating with aradiating apparatus a target within a patient resting on a patientsupport rotatable about a rotational axis, the method comprising thesteps of:

-   -   positioning the patient support such that the target is at least        partially coincident with or adjacent to a treatment volume        irradiated by the radiating apparatus and the target and        treatment volume lie along the rotational axis;    -   selectively irradiating the treatment volume when the target is        at least partially coincident with the treatment volume;    -   rotating the patient relative to the radiating apparatus; and    -   again selectively irradiating the treatment volume while        monitoring the location of the target in the adjusted position.

In one form, the method of the invention treats a target within a bodyof a patient with a radiating apparatus irradiating a treatment volumehaving a known position by the following steps:

-   -   positioning the patient such that the target to be treated is        located near the treatment volume;    -   scanning the body and creating body images of the body to        determine the position of the target relative to the treatment        volume; and    -   activating the radiating apparatus to irradiate the target when        the determined position of the target is at least partially        coincident with the known position of the treatment volume.

In another form, the invention comprises a system for treating a targetwithin a body of a patient, wherein the system comprises:

-   -   a radiating apparatus irradiating a treatment volume having a        known position;    -   a scanner scanning the body and creating body images of the body        to determine the position of the target; and    -   a controller responsive to the scanner for activating the        radiating apparatus to irradiate the target when the position of        the target as determined by the scanner is at least partially        coincident with the known position of the treatment volume.

Other objects and features will be in part apparent and in part pointedout hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one preferred embodiment of the systemaccording to the invention in which a controller selectively activates aproton beam radiating apparatus, including a partial end elevation viewof a patient support.

FIG. 2 is a block diagram of another preferred embodiment of the systemaccording to the invention in which the controller selectively activatesthe proton beam radiating apparatus in response to operator input froman operator viewing a display of body images and a reference image.

FIG. 3 is a block diagram of another preferred embodiment of the systemaccording to the invention in which the patient support is adjustedduring irradiation to maximize the time the treatment volume and targetare coincident or adjacent.

FIG. 4 is a lateral elevation view of the patient support showing thepatient on the platform of the patient support.

FIG. 5 is a lateral elevation view of the patient support showing thepatient on the platform after the patient support has been adjusted sothat the target and the rotational axis lie within the samesubstantially horizontal plane (e.g., X-Z plane).

FIG. 6 is an end elevation view of the patient support wherein theupright supporting mechanism is centered on the base frame.

FIG. 7 is an end elevation view of the patient support wherein theplatform has moved horizontally and is positioned to the right ascompared to FIG. 6.

FIG. 8 is an end elevation view of the patient support wherein theupright supporting mechanism has moved horizontally to the left so thatthe platform (positioned to the right) is centered over the base frame.

FIG. 9 is a partial end elevation view of the patient supportillustrating the operation of the strut screw drive as it moves thestrut along the patient rotation plate in a substantially verticalfashion.

FIG. 10 is a partial top elevation view of the patient on the patientsupport before adjustment of the patient support.

FIG. 11 is a partial top elevation view of the patient on the patientsupport after the patient support has been adjusted within the MRImagnets so that the target and treatment volume lie within the samesubstantially horizontal plane.

FIG. 12 is a flow chart illustrating the main steps of the treatmentmethod used by the present invention.

Those skilled in the art will note that the drawings are not to scaleand certain shapes and volumes have been enlarged for viewingconvenience.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In general, the system 100 of the invention is a near-simultaneous,noninvasive localization and radiotherapy device capable of detectingand treating malignancies, benign tumors, and normal tissues of variouscell lines in any anatomic location within the body.

Magnetic resonance imaging (MRI) is a noninvasive diagnostic imagingtechnique which uses powerful magnetic fields and rapidly changingradio-frequency energy pulses to tomographically represent the variedfat and water content within living tissues. Using standard,cylindrical, closed-bore magnet designs, MRI is extremely useful for thedetection and localization of tumors, some of which may not be detectedusing X-ray computed tomography (CT). The open-architecture design ofnewer MRI units (e.g., units 156) has extended the utility of standardMRI by permitting the imaging of claustrophobic patients, and bypermitting intra-operative imaging in real time during surgery. Protonbeam therapy can be combined with MRI or other scanners to minimizecollateral radiotoxicity to the surrounding normal tissues by gating thedelivery of the proton beam (e.g. beam 111) during physiologic cycles.

The primary physiologic cycles considered are the respiratory andcardiac cycles. However, other physiological movements, such as thoserelated to voluntary or involuntary muscular activity (such asperistalsis), can also be accommodated with this technique. Becauseabdominal as well as diaphragmatic movement may adjust the position ofthe tumor during the respiratory cycle, the position of the patient mustbe adjusted for each of these movements. Rapid MRI acquisition minimizesthe need for patient breath-holding during treatment.

While open MRI units are required in the preferred embodiment of thepresent invention, it is acknowledged that other embodiments of thepresent invention may be compatible with standard, closed-bore MRIunits. It is not intended that such embodiments be outside the scope ofthe present invention, and, in fact, any type of compatible MRI may beused.

Further, while it is acknowledged that MRI systems are currently theonly scanners compatible with the other technologies required in thepresent invention, it is not intended that the present invention belimited to such scanning systems, and, in fact, any compatible scannercapable of imaging the body may be used.

Referring first to FIG. 1, a block diagram illustrates the maincomponents of one preferred embodiment of a system of the presentinvention. A patient 142 has tumorous tissue, such as a target 146, tobe irradiated by a proton beam 111. A proton beam radiating apparatus110 located outside of a pair of magnets 116 of an MRI unit 156 emitsthe proton beam 111 which first passes through an optional waterattenuator 112. The proton beam 111 then passes through an optional beampipe 114 located within one of the magnets 116 before entering thepatient 142. The proton beam 111 focuses on a treatment volume 144within the patient 142 and is activated when the treatment volume 144 isat least partially coincident with the target 146. The attenuator 112and beam pipe 114 are used, if needed, to position the treatment volume144 between the magnets 116. Activation of the proton beam radiatingapparatus 110 occurs through the use of an activation signal 153received from a controller 150. The controller 150 sends the activationsignal 153 when body images 154 received from the MRI unit 156 indicatethat the target 146 as defined by a reference image 152 from an earlierMRI scan overlaps the treatment volume 144. The reference images 152reside in memory accessible by the controller 150.

The patient 142 rests on a patient support 130 comprising asubstantially horizontal platform 134 supported by a pair of uprightsupporting mechanisms 136 on either end of the platform 134 (e.g., headand toe) connected to a base frame 148 on casters. The patient support130 resides between the magnets 116 of the MRI unit 156. The patientsupport 130 adjusts within an XYZ-axis coordinate system. The X-axisextends side to side along the width of the patient 142. The Y-axisextends front to back along the depth of the patient 142, substantiallyperpendicular to the base frame 148. The Z-axis, as shown in FIG. 4,extends from head to toe along the longitudinal axis defining the heightof the patient 142. The operation of the system of FIG. 1 will bedescribed below.

Referring next to FIG. 2, the components and their connectionscorrespond to FIG. 1 except that the body images 154 and the referenceimage 152 appear on a display 260 viewed by an operator 151 who manuallycontrols the system rather than providing the images to the controller150 for automatically controlling the system. While viewing the display260, the operator 151 signals the controller 150 via a keyboard ortouch-screen to provide operator input to send the activation signal 153to the proton beam radiating apparatus 110 to activate the proton beam111 selectively. The operator 151 signals the controller 150 to send theactivation signal 153 when the body images 154 received from the MRIunit 156 indicate that the target 146 at least partially overlaps thetreatment volume 144. Similarly, the operator 151 signals the controller150 to send the de-activation signal when the body images 154 indicatethat the target 146 has moved out of coincidence with the treatmentvolume 144. The operation of the system of FIG. 2 will be describedbelow.

Referring next to FIG. 3, the components and their connectionscorrespond to FIG. 1 with the addition of motors 300 connected to thepatient support 130. The motors 300 operate in response to a positioningdevice 358 (e.g., a control board) within the controller 150 to adjustthe patient support 130 to maximize the time that the target 146 andtreatment volume 144 are coincident. The motors 300 may be energized tomove the target 146 so that it at least partially overlaps the treatmentvolume 144. Alternatively, the motors 300 may be energized to counterphysiologic motion to maintain the target 146 within the treatmentvolume 144. For example, because breathing represents a commonphysiologic cycle, in one embodiment the motors 300 could raise or lowerthe platform 134 to offset any down or up breathing motion of thepatient 142 which maximizes the time that the target 146 and treatmentvolume 144 are coincident. The operation of the system of FIG. 3 will bedescribed below.

The potential repositioning action during the treatment to achievemaximal time of coincidence with the treatment volume 144 may createmechanical and radio-frequency (RF) noise which could effect the MRIquality. Repositioning the platform 134 in the Z-axis only to accountfor the majority of respiratory variability should maximize treatmenttime in the target window while minimizing noise.

Referring next to FIG. 4, a lateral elevation view of the patientsupport 130 is shown. Initially, the patient 142 is placed on theplatform 134 and moved into position along the Z-axis so that the target146 and the treatment volume 144 are located in or near the samevertical X-Y plane. As FIG. 4 indicates, the target 146 and treatmentvolume 144 may not be coincident and may be located in different,non-adjacent planes. The upright supporting mechanisms 136 connect toopposing ends of the base frame 148 of the patient support 130 bygearings 137.

A pivot pin 147 protrudes from each upright supporting mechanism 136 tothe interior of the patient support 130 along a Z-axis. The pivot pins147 define a substantially horizontal, rotational axis 149 of thepatient support 130 parallel to the Z-axis. A vertical patient rotationplate 139 with bearings 140 in its bored-out center is mounted on eachpivot pin 147 to permit rotation of the plates 139 about the rotationalaxis 149 parallel to the Z-axis. A pair of vertical struts 138 attach tothe pivot pins 147. One end of each strut 138 attaches to the ends ofthe pivot pins 147 interior to the patient support 130. The struts 138engage and suspend the platform 134 containing the patient 142. Onestrut 138 attaches to the pivot pin 147 above the head of the patient142 while the other strut 138 attaches to the pivot pin 147 below thefoot of the patient 142. Movement of the platform 134 relative to struts138 along the X-axis and/or movement of the upright support mechanism136 relative to base frame 148 along the X-axis positions the patient142 so that the target 146 and the treatment volume 144 are located inthe same Y-Z plane.

Referring next to FIG. 5, the components and their connectionscorrespond to FIG. 4 except that the portion of the struts 138 relativeto pins 147 has been adjusted so that the target 146 and the treatmentvolume 144 are located in or near the same X-Z plane. The struts 138have been repositioned as compared to FIG. 4 to raise the platform 134along the Y-axis relative to the pivot pins 147 so that the target 146and treatment volume 144 lie within the same substantially horizontalplane as the rotational axis 149.

Referring next to FIG. 6, an end elevation view of the patient support130 illustrates one preferred embodiment of the present invention inwhich the upright supporting mechanisms 136 is attached by the gearings137 to the center of the end rails of the base frame 148. FIG. 6 showsthe initial positions (similar to FIG. 4) of the elements of the patientsupport 130 relative to one another. The position of the platform 134 isadjustable along the X-axis by the motor 300 driving a mechanicallythreaded platform screw 145. The patient rotation plates 139 pivotallyattach to the top ends of the upright supporting mechanisms 136. As themotor 300 which is affixed to platform 134 turns platform screw 145which threadably engages the strut 138, the strut 138 moves closer to oraway from the motor 300. As a result, platform 134 moves side to siderelative to the strut 138, as shown in FIG. 7. In another embodiment,the gearings 137 are absent and the upright supporting mechanisms 136are fixedly centered on the ends of the base frame 148. As above, theplatform 134 moves side to side relative to the strut 138.

Referring next to FIG. 7, an end elevation view of the patient support130 illustrates one preferred embodiment of the present invention inwhich the upright supporting mechanisms 136 is mounted on the gearings137 moveable along the X-axis and platform 134 is moveable along theX-axis relative to the struts 138. It is contemplated that either thegearings 137 and/or the platform screw 145 may permit movement of theplatform 134 along the X-axis. FIG. 7 shows the position of the platform134 after it has been moved to the right relative to the struts 138 bythe motor 300, the platform 134 moving in the direction as indicated byan arrow 7.

Referring next to FIG. 8, the components and their connectionscorrespond to FIG. 7 except that the base frame 148 has been moved viathe gearings 137 along the X-axis as indicated by an arrow 8 to theright to center the platform 134 over the base frame 148.

Referring next to FIG. 9, a partial end elevation view (from theinterior toward the exterior) illustrates one of the patient rotationplates 139 and its connection to the strut 138. The pivot pin 147protrudes along the Z-axis from the upright supporting mechanism 136(not shown in FIG. 9), through the patient rotation plate 139 to thestrut 138. The strut 138 adjusts along the Y-axis by the motor 300connected to a mechanically threaded strut screw drive 143. A guide pin141 located near the perimeter of the patient rotation plate 139 extendsfrom the patient rotation plate 139 through the strut 138 into a slot141 to cause the patient rotation plate 139 and strut 138 to rotatetogether about the Z-axis.

Referring next to FIG. 10, a top view of the patient 142 on the patientsupport 130 within the magnets 116 illustrates that the target 146 andtreatment volume 144 are initially not coincident. The patient 142 restson the patient support 130 located between the two magnets 116 of theMRI unit 156. The proton beam 111 enters the MRI unit 156 through thebeam pipe 114 and focuses on the treatment volume 144.

Referring next to FIG. 11, the components and their connectionscorrespond to FIG. 10 except that the position of platform 134 andpatient 142 has been adjusted so that the target 146 and treatmentvolume 144 are coincident. The patient support 130 has been moved alongthe X and Z axes (as noted above) to achieve coincidence in the X-Y andX-Z planes between the target 146 and treatment volume 144.Alternatively, the proton beam 111 may be attenuated so that the target146 and treatment volume 144 align along the X-axis. The platform 134may also be moved along the Y-axis (as noted above) to achievecoincidence in the X-Z plane.

In general, the invention comprises the system 100 for treating thetarget 146 within the body of the patient 142, wherein the systemcomprises:

-   -   the radiating apparatus 110 irradiating the treatment volume 144        having the known position;    -   the scanner 116, 156 scanning the body 142 and creating the body        images 154 of the body to determine the position of the target        146; and    -   the controller 150 responsive to the scanner 116, 156 for        activating the radiating apparatus 110 to irradiate the target        146 when the position of the target 146 as determined by the        scanner 116, 156 is at least partially coincident with the known        position of the treatment volume 144.        Operation

To irradiate the target 146 within the patient 142, the treatment planevolves as follows. The MRI unit 156 pre-operatively scans the patient142 to obtain the reference image 152 of the target 146. Based on thisreference image 152 and its location within the patient 142, thetreatment plan incorporates the number and angle of the irradiations.The reference image 152 also aids in relocating the target 146 afterrepositioning the patient 142 within the MRI unit 156 for subsequenttreatments.

Paramagnetic agents are used for tumor enhancement. It is anticipatedthat paramagnetic agents may be utilized during treatment for patientpositioning. These agents can have physiologic effects (e.g., gadoliniumreduces the heart rate) which may require an adjustment of the protonbeam gating.

It is contemplated that injectable agents can interact with the beam ona dose determined basis. These agents would vary their MRIcharacteristics during treatment so that the MRI scan would indicatewhen a specific amount of dose had reached the target, and also indicateany scatter of radiation within the patient, to assist in the deliveryof radiation to the patient. In this way any error in the treatment plancould be compensated for during the actual treatment.

To implement the treatment plan, the target 146 within the patient 142and the treatment volume 144 must be at least partially coincident. Thetreatment volume 144 is the location of the Bragg peak for the protonbeam 111. The patient 142 is positioned on the support 130 and thesupport 130 is placed between the two magnets 116 of an open MRI unit156 as illustrated in FIG. 1 and FIG. 4. The MRI unit 156 provides bodyimages 154 of the patient 142 to the controller 150 or operator 151searching for the area of the location of the reference image 152 withinthe patient 142. When the body images 154 correspond to the referenceimage 152 and locate the target 146, the position of the patient 142 onthe patient support 130 is adjusted as noted above along the Y and Zaxes so that the target 146 lies along the X-axis path of the protonbeam 111. Attenuating the proton beam 111 with the water attenuator 112adjusts the location of the treatment volume 144 along the X-axis sothat the target 146 and the treatment volume 144 are at least partiallycoincident or adjacent. Alternatively, the position of the patient 142on the patient support 130 may be adjusted as noted above along theX-axis so that the target 146 at least partially coincident with thetreatment volumes 144 so that the attenuation of the proton beam 111need not be changed.

The target 146 may shift as a result of physiologic motion (e.g., therespiratory or cardiac cycle). Because the target 146 may be subject tosignificant physiologic motion, the controller 150 or the operator 151selectively activates the proton beam 111 when the target 146 andtreatment volume 144 are at least partially coincident. In a preferredembodiment, the controller 150 automatically gates the proton beam 111based on feedback circuits and body images 154 to maximize the amount oftreatment that the target 146 receives while in the treatment volume144. In the preferred embodiment, the controller 150 uses a physiologictrigger based on the respiratory cycle which has been previouslyevaluated by MRI to estimate the normal extent of diaphragmaticexcursion. However, in general, the controller 150 need only controlactivation and deactivation of the proton beam 111 and, in one form, maybe a timer to activate the beam for a set period.

Operator 151 control presumably would introduce inefficiency and delayin the operation of the proton beam 111 reducing the amount of time thattreatment is delivered to the target 146. However, a respiratory device400 around the patient 142 determines the onset of inspiration whichacts as a signal for treatment to reduce operator 151 effort andcontroller 150 mistakes. Preferably, the respiratory device 400 is astretchable belt that expands and contracts as the patient 142 inhalesand exhales. Determining the onset of inspiration requires apre-programmed abdominal and diaphragmatic motion range obtained fromthe pre-treatment MRI study.

When the target 146 moves out of the treatment volume 144, thecontroller 150 or the operator 151 signals the proton beam radiatingapparatus 110 to de-activate the proton beam 111. When the target 146moves back within the treatment volume 144, the controller 150 or theoperator 151 signals the proton beam radiating apparatus 110 tore-activate the proton beam 111. In this manner, irradiation of themoving target 146 occurs with minimal radiotoxicity to the normalsurrounding tissues.

In another embodiment, adjusting the patient support 130 duringirradiation to compensate for the physiologic motion of the target 146maximizes the time that the target 146 and treatment volume 144 arecoincident. A positioning device 358 within the controller 150 operatesthe motors 300 to adjust the position of the platform 134 along the Xand Y axes. Motors (not shown) may also be used to rotate plate 139and/or adjust the position of platform 134 along the Z-axis. Thecontroller 150 determines whether the patient support 130 requiresadjustment to improve the degree of coincidence of the target 146 andtreatment volume 144. The controller 150 also determines the directionand distance of the adjustment. Those skilled in the art will note thatthe controller 150 could be designed to adjust the patient support 130in any spatial dimension as well as rotation about the rotational axis149. For example, because breathing represents a common physiologiccycle, in one embodiment the motors 300 could raise or lower theplatform 134 by moving the struts 138 up or down with respect to thepatient rotation plates 139 to offset the down and up breathing motionof the patient 142 and to maximize the time that the target 146 andtreatment volume 144 are coincident.

Preferably, the patient 142 should be repositioned along the Z-axis tocoordinate physiologic motion to treatment volume 144. Repositioning thepatient 142 in anything other than the Z-axis in a time frame that wouldallow for the connection of physiologic motion to treatment activationmay be more difficult to achieve. Further, prior to treatment, thenormal respiratory cycle range of diaphragmatic excursion for thepatient 142 as well as the maximum range of deep breathing can bedetermined. The impact of this respiratory range (normal and maximal) onliver and lung positioning can be used to program the controller 150 tomove the patient support 130 to maximize coincidence between the target146 and treatment volume 146 during treatment.

Referring to FIG. 12, a flow chart illustrates the basic steps forirradiating the target 146. A first step 201 positions the patientsupport 130 appropriately. A second step 202 selectively irradiates thetreatment volume 144 while monitoring the location of the target 146with MRI. If successive irradiations are necessary, then a third step203 rotates the patient 142 and performs additional monitoredirradiations. The second and third steps 202, 203 repeat as many timesas necessary after each rotation step 203 according to the treatmentplan. The treatment ends when no more irradiations are required.

In particular, the first step 201 involves positioning the patientsupport 130 so that the target 146 within the patient 142 is coincidentwith or near the treatment volume 144 (i.e., Bragg peak) of the protonbeam 111. The second step 202 irradiates the target 146 while the target146 and the treatment volume 144 are at least partially coincident. TheMRI monitors the location of the target 146 while the controller 150 orthe operator 151 selectively activates and deactivates the proton beamradiating apparatus 110 as described above to minimize the collateraltissue damage. If successive irradiations are required from differentangles according to the treatment plan, then in the third step thepatient 142 is moved (e.g., rotated about the Y or Z axes) relative tothe proton beam radiating apparatus 110 and again selectivelyirradiated. The patient 142 is rotated about the target 146 about theY-axis by rotating the base frame 148 on its casters about the Y-axis.The patient 142 is rotated about the target 146 about the Z-axis byturning the patient rotation plates 139 about pin 147. Alternatively,the proton beam radiating apparatus 110 may rotate about the treatmentvolume 144. Proton accelerators are already manufactured which allow thebeam pipe to rotate about the patient. This rotation could occur withinthe gap between the two magnet of the MRI unit. Preferably, the patient142 rotates about the Z-axis relative to the proton beam radiatingapparatus 110 approximately 80 degrees in either a clockwise orcounterclockwise direction while maintaining the coincidence of thetreatment volume 144 with the target 146. The rotation and selectiveirradiation of the target 146 repeats as many times as necessaryaccording to the treatment plan.

The first step 201 in the method for irradiating the target 146,positioning the patient 142 so that the target 146 and treatment volume144 are coincident, comprises several substeps which may be performed invarious sequences. Those skilled in the art will recognize that thereare several ways not specifically detailed herein to manipulate thepatient support 130 to achieve coincidence between the target 146 andthe treatment volume 144.

The first substep involves positioning the target 146 and the rotationalZ-axis 149 within the same substantially vertical Y-Z plane by movementalong the X-axis (see arrow 210 in FIG. 10). The position of the uprightsupporting mechanisms 136 adjust along the X-axis by a set of thegearings 137 as in FIG. 8. The platform 134 moves along the X-axis onthe ends of the struts 138 by the mechanically threaded platform screwdrive 145 as in FIG. 7. As the platform 134 is adjusted in one directionalong the X-axis as in FIG. 7, the upright supporting mechanism 136 maybe adjusted in the opposite direction as in FIG. 8 to maintain theposition of the platform 134 centered over the base frame 148. Theupright supporting mechanism 136 and platform 134 adjust in this manneruntil the target 146 and the rotational axis 149 lie within the samesubstantially vertical X-Y plane. Centering the platform 134 over thebase frame 148 prevents the patient support 130 from tipping over due tothe target 146 being located near either outer edge of the platform 134.If the upright supporting mechanisms 136 is fixedly attached to the baseframe 148 (not shown), only the platform 134 moves along the X-axis toplace the target 146 in the same vertical Y-Z plane as the rotationalaxis 149 or the base frame 148 moves on its casters to achieve the sameresult. In FIG. 10, the target 146 would be moved left.

The second substep in positioning the patient 142 involves adjusting theheight of the platform 134 by movement along the Y-axis so that thetarget 146 and the rotational axis 149 lie within the same substantiallyhorizontal X-Z plane (see arrow 220 in FIG. 4). Referring to FIG. 9, themechanically threaded strut screw drives 143 attach to each strut 138.The strut screw drives 143 raise or lower the platform 134 along theY-axis depending on the location of the target 146 so that the target146 and the rotational axis 149 of the patient support 130 lie withinthe same substantially horizontal plane.

The third substep in positioning the patient 142 involves placing thetarget 146 within the path (or within the vertical X-Y plane) of theproton beam 111 by movement along the Z-axis. To locate the target 146within the path of the proton beam 111, the patient support 130 is movedinto place on its casters between the magnets 116 of the MRI (see arrow230 in FIG. 10).

In the fourth substep to position the patient 142, the position of thetarget 146 is adjusted along the X-axis relative to the Bragg peak ortreatment volume 144 of the proton beam 111 so that the treatment volume144 is coincident with the target 146. In one embodiment, the locationof the treatment volume 144 is adjusted along the X-axis by attenuatingthe proton beam 111 with the water attenuator 112. Those skilled in theart will notice that the attenuation of the proton beam 111 can beaccomplished in several different ways not specifically describedherein. Alternatively, the patient support 130 may be moved on itscasters along the X-axis until the target 146 is near or coincident withthe treatment volume 144.

An additional, fifth substep may be required to position the target 146and the treatment volume 144 within the same substantially horizontalX-Z plane. Preferably, the vertical distance from the floor to therotational axis 149 equals the distance from the floor to the center ofthe treatment volume 144. Since the target 146 has been aligned with theaxis 149 by substeps one and two, this alignment is preset and thissubstep need not be performed. Alternatively, the upright supportingmechanism 136 may telescope along the Y-axis so achieve this alignmentand perform this substep.

In general, the above substeps may be performed in various sequences. Inone embodiment, the target is located in the XYZ grid using MRI andpatient repositioning occurs through the use of skin surface markersrelative to anatomic landmarks such as a thoracic spinal process or thexiphoid process. In another embodiment, the location of the target 146is physically marked by marks on the patient 142 and each substep isperformed by a technician who visually aligns the marks with therotational axis 149 (substeps one and two) and aligns the marks with thetreatment volume 144 (substeps three, four and five). Alternatively,each substep can be performed by using the MRI scans themselves whichdepict the target to locate the target 146 and comparing determinedlocation with the known location of the treatment volume 144. As inFIGS. 1 and 2, the given reference image 152 has certain characteristicswhich allow the controller 150 or the operator 151 to recognize thetarget 146 as the MRI scan progresses. To identify the location of thetarget 146, the controller 150 or the operator 151 compares the bodyimages 154 to the reference image 152. With knowledge of the path of theproton beam 111, the controller 150 or the operator 151 further adjuststhe patient support 130 so that the target 146 lies within the path ofthe proton beam 111.

In one aspect, it is important that the target 146 be aligned with therotational axis 149. With this alignment, rotation about the rotationalaxis 149 does not require any realignment or performing any of thesubsteps over again after rotation.

In general, the method of the invention treats the target 146 within thebody of the patient 142 with the radiating apparatus irradiating thetreatment volume 144 having the known position by the following steps:

-   -   positioning the patient 142 such that the target 146 to be        treated is located near the treatment volume 144;    -   scanning the body and creating the body images 154 of the body        to determine the position of the target 146 relative to the        treatment volume 144; and    -   activating the radiating apparatus 110 to irradiate the target        146 when the determined position of the target 146 is at least        partially coincident with the known position of the treatment        volume 144.

The accompanying mechanics of the proton beam 111 and positioningdevices may have variable effects on the MRI RF pulses, or on othermagnetic fields and gradients (B₁). For example, the movement of heavymetal devices will affect the overall B₀ field, and may create “eddying”effects that could distort images. Such effects may require shielding orother compensation to avoid distorted images. Alternatively, thepositioning device could be fabricated partially or totally out ofmaterials that do not interfere with, or cause distortion in, the MRIscans. In addition, if the proton beam treatment changes the tissues perse and their imaging characteristics acutely or changes the physiologyof respiration, these changes may require revised repositioningadjustments.

While particular embodiments of the invention have been shown anddescribed, it will be obvious to those skilled in the art that variouschanges and modifications may be made without departing from the presentinvention in its broader aspects. It is intended that all mattercontained in the above description and shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

1. A method for treating a target within a body of a patient, saidmethod comprising: irradiating a treatment volume having a knownposition; supporting the patient such that the target is adjacent to thetreatment volume; scanning the body to monitor the position of thetarget; selectively activating a radiating apparatus in response to themonitored position of the target to irradiate the target when the targetis at least partially coincident with the treatment volume; andselectively deactivating the radiating apparatus in response to themonitored position of the target when the target is not at leastpartially coincident with the treatment volume.
 2. The method of claim 1wherein said supporting the patient includes adjusting an uprightsupporting mechanism supporting the patient so that the target is atleast partially coincident with the treatment volume.
 3. The method ofclaim 2 wherein said supporting the patient further includes adjusting aplatform supporting the patient so that the target is at least partiallycoincident with the treatment volume.
 4. The method of claim 3 whereinsaid supporting the patient further includes adjusting the position ofthe patient so that the target is at least partially coincident with thetreatment volume.
 5. The method of claim 4 wherein said supporting thepatient further includes moving the patient so that the target islocated along a line as defined by the radiating apparatus and thetreatment volume.
 6. The method of claim 5 wherein said supporting thepatient further includes attenuating the irradiating so that thetreatment volume is at least partially coincident with the target. 7.The method of claim 1 further comprising rotating the patient relativeto the radiating apparatus and again selectively irradiating thetreatment volume in the adjusted position.
 8. The method of claim 1further comprising rotating the patient relative to the radiatingapparatus by rotating the patient relative to the target.
 9. The methodof claim 1 further comprising rotating the patient relative to theradiating apparatus by rotating the radiating apparatus relative to thetreatment volume.
 10. A method for treating a target within a body of apatient with a proton beam radiating apparatus having a Bragg peakirradiating a treatment volume having a known position, said methodcomprising: positioning the patient such that the target to be treatedis located near the treatment volume; scanning the body to determine theposition of the target relative to the treatment volume; activating theproton beam radiating apparatus to irradiate the target when thedetermined position of the target is at least partially coincident withthe known position of the treatment volume; and deactivating the protonbeam radiating apparatus when the determined position of the target isnot at least partially coincident with the treatment volume.
 11. Themethod of claim 10 wherein said positioning the patient includesadjusting an upright supporting mechanism supporting the patient so thatthe target is at least partially coincident with the treatment volume.12. The method of claim 11 wherein said supporting the patient furtherincludes adjusting a platform supporting the patient so that the targetis at least partially coincident with the treatment volume.
 13. Themethod of claim 12 wherein said supporting the patient further includesadjusting the position of the patient so that the target is at leastpartially coincident with the treatment volume.
 14. The method of claim13 wherein said supporting the patient further includes moving thepatient so that the target is located along a line as defined by theradiating apparatus and the treatment volume.
 15. The method of claim 14wherein said supporting the patient further includes attenuating theirradiating so that the treatment volume is at least partiallycoincident with the target.
 16. The method of claim 10 furthercomprising rotating the patient relative to the radiating apparatus andagain irradiating the treatment volume in the adjusted position.
 17. Themethod of claim 10 further comprising rotating the patient relative tothe radiating apparatus by rotating the patient relative to the target.